The ore of Uranium found in nature contains $_{92}^{238}\text{U}$ and $_{92}^{235}\text{U}$. Although both the isotopes are fissionable, it is found out experimentally that one of the two isotopes is more easily fissionable.
(i) Name the isotope of Uranium which is easily fissionable.
(ii) Give a reason for your answer.
(iii) Write a nuclear reaction when Uranium 238 emits an alpha particle to form a Thorium (Th) nucleus.
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(i) $_{92}^{235}\text{U}$ is easily fissionable.
(ii) The reason is that the fission of $_{92}^{238}\text{U}$ nucleus is possible only by the fast neutrons, while the fission of $_{92}^{235}\text{U}$ nucleus can be done by both slow as well as fast neutrons.
(iii) $_{92}^{238}\text{U}$ ⟶ $_{90}^{234}\text{Th}$ + $_{2}^{4}\text{He}$